1. Field of the Invention
The present invention relates to a buckle having a three-way strap and used for securing a human body and the like.
2. Description of the Related Art
Conventionally, a buckle mounted to each coupling end portion of a three-way strap comprises a pair of plugs and a socket into and with which the pair of plugs are inserted and engaged. A through hole in a predetermined shape is formed in the socket. An operating portion for resiliently deforming the engaged buckles for disengagement is formed in the through hole. The operating portion is integrally formed at a tip end of a hinge portion which is a resilient portion formed integrally with the socket.
An engaging operation of such a buckle is reliably carried out by inserting the plugs into inserting holes of the socket and pushing the plugs against a resilient force generated in the engagements. In order to pull the plugs out of the socket, the operating portion such as a lock canceling button of the socket is pushed. Thus, the engagements between engaged portions of the plugs and the socket are disengaged, thereby the pair of plugs can be pulled out of the socket.
In the case of above prior art, because the operating portion such as the lock canceling button of the socket has a cantilevered structure wherein the operating portion is formed via the hinge portion which is integral with the socket, a sufficient spring strength can not be obtained. Thus, clothes or other members may be caught in the through hole wherein the lock canceling button is positioned, and the lock canceling button may be stripped off outward and broken. Also, displacement when the operating portion is pushed is not equal and the displacement is larger at a portion farther from the hinge portion. Therefore, the engagement of one of the pair of plugs with larger displacement disengages earlier. As a result, there may be a dispersion of feelings at the time of disengagement.
A buckle wherein displacement of the operating chip is equal is disclosed in Japanese Patent Application Laid-open Publication No. 8-89314. In this buckle, a lock member as an operating portion is separated from a socket. Two resilient leg portions projecting diagonally downward are formed at a bottom face of the lock member to abut on an inner side of a bottom face of the socket, and the lock member can be supported for projecting and sinking movements. In this buckle, both sides of the lock member can be evenly displaced by the pair of resilient leg portions.
However, because engaging portions for engagement with the plugs are formed integrally with the lock member, if "wear-out" or the like is generated in the resilient leg portions, firm and stable engagements between the plugs and the socket are hindered. Also, because the engaging portions are formed to project from opposite sides of the lock member, the lock member itself is larger than a through hole of the socket. Therefore, in assembling, the lock member is required to be inserted through the inserting hole with the resilient leg portions being resiliently deformed, thereby efficiency of the operation decreased.